M4 noise problem (urgent)

Hello.
I have a noise problem with my M4 ATX.When i start the computer after 4-5 seconds a noise starts coming from the speakers if i start the car the noise increases as i throotle up.
I know that you are going to say ground problem,thats what i thought at start,so i begun to checking everything until i get to M4.

I have for source an Alpine 9882 Ri,and bought the original alpine cable to make an aux in,all the test made with the cable on the air to check if it is ok.I do not have an amplifier and i use for the speakers the amplifier of the alpine.

Thats what i did
1.checked all grounds-everything ok
2.removed the step down from 12v to 5v-Still have noise
3.all the power cables where from one side (drivers side) i even still removed them out and still have noise
4.made a half meter only ground cable and connected it to a clear spot to the drivers seat belt just in case that because i had 2 meter before ground cable
made noise.Still have noise
5.Removed all usb-still noise

Then i believed something was wrong with the computer so
1.removed everything from inside the computer (including the M4 ATX)and builted it outside the car in case that i had somewhere problem with my box grounding something that i couldnt see),nothing still the same noise.

I Even took 2 new cables from the battery took them outside the car and powered the M4 STILL THE SAME NOISE

so finally i removed the M4 ATX and connected its regular power supply AC powered.SUCCESS no parasite sound no more.

Another thing is that i noticed that when i took the ground cable out while the computer was working nothing stopped and continued to work with only the 12v cable connected.How is this possible?

I am working to eliminate this noise for about a week now i already have again half of the car disassembled,My nerves arent in a good situation,and i stopped just to write to you because if i continue thinking inside the car i WILL BREAK EVERYTHING INSIDE.

Does anyone had any similar problem?Any suggestions?Shall i return the M$ back or there is something that i can do?

Sounds like youīve done the usual save maybe moving grounding points to see if it improves.

Iīve seen numerous threads with issues on the M4 and the M2 for RFI and just generally having noise issues. See this thread with Mickz entries on it. The last 3 pages have his particular solution if your set on keeping it. I think heīs got a thread on exact details on how he built it as well, but canīt find the thread right off here. General idea of using feed-through caps with an aluminium case to eliminate the noise, in his case more for the RFI that was occurring, messing with his GPS and such.

The grain of salt should of course be taken, as this model seems to be the most popular as well, so it will of course have the most posted issues. That said, I do see many having issues of one sort or another with them, some can readily be played off as user error, others not so much.

Still no guarantee really, as you might just be unlucky, and have an usually noisy alternator or noise creeping into your lines. In which case sending it back might not help, but if you didnīt note anything with the previous unit, itīs a fair bet you could get another with a bit better filtering that will likely work better in your set-up. My personal preference is an opus.

Another thing is that i noticed that when i took the ground cable out while the computer was working nothing stopped and continued to work with only the 12v cable connected.How is this possible?

Assuming you have parts of the PC bolted, or anything else in the potential circuit grounded via the frame it can then use that for itīs ground. Which is something of course you donīt want.

so if i get this right.I must make an aluminium case for the M4 and thats it?i am going to get crazy with that thing

No, it would take using feed capacitors for the case to eliminate it. I think the price-tag came in around $54 for all the caps that youīd potentially need to do it. Not including case, soldering, fan, etc..

Keep in mind this can be a severe PIA even with a decent sold one and good grounding. I still have a very slight bit of it at the start until the sound-card is initialized by win7. Itīs very faint, but there. Comes through on my 3.5mm to RCA adapter. If it bugs me enough later I might try to find some with some better shielding, or just run it directly inside the carPC.

I coulda sworn he had another thread on it for his, but I searched a few terms I thought would be in it and am coming up empty. However, page 12 of that thread states the details of what he did. The back and forth in the following ones gives an example of the purchased feed through caps that can be used, purchased through mouser electronics.

If your simply looking to eliminate the alternator whine making itīs way into the PSU, Iīd think you could just get away with using feed through caps on just the hot lines going as input(12v constant, 12v ACC) to the M4. Rather than the more elaborate means he used to eliminate all of his noise issues not only emanating from the car, but the PSU itself.

I coulda sworn he had another thread on it for his, but I searched a few terms I thought would be in it and am coming up empty. However, page 12 of that thread states the details of what he did.

yes i read it but i dont have so much knowledge unless i find a how to so everything is done ok.the thing that i can not understan is why when the m4 was while testing out of the pc box and also the motherboard out of the pc box and about 20 cm away the one from the other it still made noise.i forgot to mention that everytime i got out of the car i had static electricity on me when i touched the door.

yes i read it but i dont have so much knowledge unless i find a how to so everything is done ok.the thing that i can not understan is why when the m4 was while testing out of the pc box and also the motherboard out of the pc box and about 20 cm away the one from the other it still made noise.i forgot to mention that everytime i got out of the car i had static electricity on me when i touched the door.

Not sure if I understand that correctly, but your asking why it has the alternator noise even though you hooked it up outside the car? So long as the car is running, and your using power/ground from the vehicle, that wonīt save it.

Getting out of most cars (most notably in winter when thereīs less humidity) youīll usually generate a decent amount of static electricity. Unless your fiddling with your stuff at that time, your fine. This is why your not supposed to get in and out of your car while fueling, or if you do, to touch your frame briefly away from the filling point once your out of the vehicle again.

You have hooked up another AC PSU with the carpc hooked up in the car, right? As to eliminate the lines and such going to the amp (and the amp itself) as the culprits?

If youīve narrowed it down completely to the M4, your only 2 options that are realistic are:
1) return it and hope for better luck with another
2) or making what essentially amounts to a filtered faraday cage that Mickz made.

the noise was coming even when i connected it straight to the car battery without running the engine.
When i putted a regular ac atx everything worked great no noise.
Sorry for my english they arent so good

the noise was coming even when i connected it straight to the car battery without running the engine.
When i putted a regular ac atx everything worked great no noise.
Sorry for my english they arent so good

Aaaaaah, so your saying itīs emitting some kind of noise even if the car isnīt running? In that case, ya, Iīd just return it and get something else and be done with it. Sounds like a severe RFI problem.